Wafer-Scale Transducer Coating and Method

A miniature ultrasonic transducer, comprising:

• a substrate having a first side and a second side opposite the first side;
• a well disposed in the substrate, the well being filled with a backing material;
• a transducer membrane disposed over the first side of the substrate and over the well, the transducer membrane containing a piezoelectric layer;
• a first conductive layer disposed over the transducer membrane;
• a second conductive layer disposed below the transducer membrane;
• a first bond pad disposed on the first conductive layer;
• a second bond pad disposed on the second conductive layer;
• and
• a protective layer disposed over the transducer membrane and over the first and second conductive layers, wherein the protective layer contains recesses that expose the first and second bond pads.

A method of fabricating a miniature ultrasound transducers, the method comprising:

• receiving a wafer on which a plurality of miniature ultrasound transducers are formed, the miniature ultrasound transducers each including:
• a transducer membrane that contains a piezoelectric material;
• and
• a first bond pad and a second bond pad each electrically coupled to the transducer membrane;
• conformally depositing a protective layer over the plurality of miniature ultrasound transducers from a front side of the wafer;
• performing a first etching process to form a plurality of first trenches that extend into the wafer from the front side, wherein the first trenches are etched through the protective layer, and wherein the first trenches are disposed between adjacent miniature ultrasound transducers;
• and
• performing a second etching process to remove portions of the protective layer disposed over the first and second bond pads, thereby exposing the first and second bond pads.